Monday, 9 June 2014

Esophageal Cancer

Esophagus is a part of Upper Gastrointestinal Tract and is the food
pipe in layman term. It connects the oropharynx to stomach & serves
the function of transfer of food from mouth to stomach by rhythmic
propulsive movement of its muscular coat. It is about 40 cm in the
length (average). The esophagus has several lining which from inside to
outside which are – lamina propria, submucosa muscularis propria and
adventitia.

Carcinoma esophagus is a cancer arising from the lining of
esophagus. It accounts for around 5% of all gastro intestinal tract
tumors. It is more common in males & its incidence increases with
age with peak in 6th to 7th decade of life.

Smoking, alcohol consumption, excess intake of food rich in
nitrosamine increases the risk of development of esophageal cancer.
Certain non malignant disorder like achalasia, gastro esophageal reflux
disease, Barett’s esophagus etc. also predisposes to developement of
carcinoma oesophagus.
The most common symptoms of Carcinoma Oesophagus is dysphagia for
solid food which can gradually increases as the tumor occludes the
lumen of esophagus. Later on patient is unable to swallow even liquids
& water. It may result in change in quality of voice, pain,
recurrent cough when the disease spread to adjacent organs.

Staging of cancer esophagus is on the basis of level of invasion of the esophageal wall (from inside to outside).

T1
is the tumor confined to inner most layer only, whereas T4 is the tumor
which involves adjacent structures outside the esophagus. The overall
prognosis is related to T-stage, involvement of draining lymph nodes
& presence or absence of distant spread. This forms the basis of TNM
staging by American Joint Committee on cancer.

Management of cesophageal cancer can be surgery if in early operable
stage or a combination of radiotherapy and chemotherapy known as
concurrent chemoradiotherapy. Surgery involves excision of the tumor
along with some healthy tissue margin & reconstruction of esophagus
to permit oral food intake. Different techniques of surgeries are used
for different tumor locations. Post operative or pre operative
chemotherapy and radiotherapy may be required in certain conditions.

With advancement in technology, the role of radiotherapy has emerged
greatly. Radiotherapy & chemotherapy used together gives results
comparable to surgery with preservation of organ. Patient who are
medically unfit for surgery or who desires organ preservation can be
treated by chemo-radiotherapy with similar tumor control & survival
rate as achieved by surgery.

Role of Radiotherapy.
Radiotherapy is a primary treatment modality in the treatment of Carcinoma Oesophagus.
In the past radiotherapy has not been used upto optimal doses
required to treat cancer, because of the limitation of the dose to
surrounding vital organs like lungs, heart, spinal cord etc.
With the advent of newer & precise techniques of radiotherapy
planning & delivery such as 3D Conformal radiotherapy &
Intensity Modulated Radiotherapy, optimal tumoricidal doses can be
delivered without crossing the tolerance limit of surrounding critical
structures.

Procedure of Radiotherapy Treatment
The process of radiotherapy treatment starts with the making of
customized plastic orfit cast (perforated thermo-plastic sheet) of
chest.

This cast is tailor made for each patient & serve the purpose of
preventing any movement at the time of radiation treatment. It also
spares the patient from having tatto marks on skin required for daily
field alignment. A Planning CT scaan of the chest is done with the
orfit cast on the patient and is used for radiation treatment planning.
The radiation oncologist then marks the tumor and other normal organs
on the treatment planning system. A physicist team then makes the
desired plan and the oncologist selects the best plan and approves it
for the treatment of patient clinically.

In our hospital the radiation treatment is usually given for
25 fractions (5 days / week from Monday to Friday). The treatment time
every day ranges between 15 – 25 minutes. The radiation is given in 2-3
phases,initially the dose is delivered to entire disease involved part
with generous margins. Later in step wise manner the radiation field is
shrinked to delivered higher doses to tumor involved part with smaller
margins. Once radiation is complete it is followed by 2 fractions of
boost radiotherapy by Intraluminal technique. In this procedure, under
local anesthesia a hollow tube is inserted in the oesophagus. This tube
is connected to radiation source and tumor can be treated with the
remaining dose (usually 2 fractions of Intraluminal Brachytherapy).

The common side effects of radiotherapy are generalized weakness,
loss of appetite and mild burning on swallowing. But these side effects
are mild and are easily manageable.

Different institution follows different chemotherapy schedules along
with radiotherapy to enhance the effect of radiation.Most commonly used
protocol are infusion of combination chemotherapy starting from D1- D5
of radiotherapy (cycle – 1) followed by similar cycles at interval of
3-4 weeks. Adding chemotherapy to radiation improves result in terms
of disease control and better survival rate.